One of the trickiest couplets in the whole Stubbs & Falk (2002) key is the very first which asks whether the humeri and hairy (subfamily Milesiinae) or bare (subfamily Syrphinae). The hairy humeri of Milesiinae are usually fairly obvious because the head tends to be rounded behind giving a clear view of the humeri. It also helps in this specimen, Brachypalpoides lenta, that the pale hair stands out well against the black of the legs.